OREANDA-NEWS.  Since January 1992, California has required all rigid plastic bottles and containers to have a molded label with one of seven resin codes to indicate the type of plastic resin used in the manufacture of these products (Public Resources Code, Division 12.7 Chapter 2 ‘Containers and Packaging’). The purpose was to facilitate the efficient sorting of used plastic bottles and containers for recycling in the state. These seven resin codes are the following:

  1. 1 = PETE (polyethylene terephthalate), commonly known as PET

  2. 2 = HDPE (high density polyethylene)

  3. 3 = V (vinyl)

  4. 4 = LDPE (low density polyethylene)

  5. 5 = PP (polypropylene)

  6. 6 = PS (polystyrene) and

  7. 7 = Other (includes multilayer)

PET is widely used in water and soft drink bottles and is used for a variety of other products. This plastic is recyclable and its flakes and pellets are commonly recycled into other types of packaging and fiber. These include, among other things, carpets and microfibers.

Polyethylene terephthalate glycol-modified (PETG) is less brittle than PET and has a softer and more pliable exterior surface.

The chemical composition of both PET and PETG consists of polyethylene terephthalate and each of these two types of plastic is labeled with resin code ‘1’. Unlike PET, PETG does not have a consistent melting point and becomes molten when heated. When both PET and PETG are processed together during recycling, the much lower processing temperature of PETG melts first and becomes sticky to solid PET chips to form large lumps that cannot be processed. These physical characteristics create significant challenges for recycling

In October 2017, California approved ‘AB 906’ (Chapter 823, Statutes of 2017)’ to create a new section in the Public Resources Code on ‘Containers and Packaging’ by providing a chemically-based definition, with specific melting point characteristics, for PET. This new definition for polyethylene terephthalate differentiates PET from PETG and has in effect excluded PETG bottles and containers from being labeled with resin code ‘1’.

The characteristics of PET in the law are summarized in Table 1.

Plastic Definition Effective Date
PET

Plastic derived from a reaction between terephthalic acid (a) or dimethyl terephthalate (b) and monoethylene glycol (c) and meeting both of the following conditions:

  • The sum of substances (a) or (b) and (c) constitutes at least 90% of the mass of the monomer reacted to form the polymer
  • 225-255 °C melting peak temperature during the second thermal scan with a heating rate of 10 °C/minute (ASTM D3418)
 October 1, 2018

Table 1

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